Conventionally, in a case of executing a copy processing or a scan processing with an image forming apparatus, a user sets a parameter such as resolution, and then presses the start button. In this way, the image forming apparatus reads an image according to the parameter, forms the obtained image data on a sheet, converts the image data into file and then stores it in a storage area.
When setting the parameters, it is necessary for the user to imagine and set the image data obtained after the image is read according to an image of the document sheet. Further, after the image is read, it is also required to confirm whether or not the read image is the desired image. As a confirmation method, the user observes the preview-display on an operation panel, or prints the preview-display on the operation panel actually, or displays the image data obtained after the image is read on a monitor of a PC (Personal Computer).
If the confirmed read image is just the desired image, the image reading job can be ended. However, in a case in which a reading image different from the desired image is generated, the user carries out the setting of parameters serving as the initial step again. That is, the user carries out the same jobs repeatedly until the desired reading image is obtained. Further, during a period in which the same jobs are carried out repeatedly, unwanted image data, which will not be adopted, is also generated and stored. As long as the unwanted image data is not deleted, it will remain as it is and compress the storage area.